In the process of production of IC devices and other electronic devices, an electronic device test apparatus is used for testing the performance and functions of the electronic devices produced.
One conventional example of an electronic device test apparatus comprises a test unit testing IC devices, a loader unit sending pre-test IC devices to the test unit, and an unloader unit taking out and classifying the tested IC devices from the test unit. Further, the loader unit is provided with a buffer stage able to move back and forth between the loader unit and the test unit, and a loader unit conveyor system having a suction unit able to pick up and hold an IC device and being able to move from a customer tray to a heat plate and from the heat plate to the buffer stage. Further, the test unit is provided with a test unit conveyor system having a contact arm able to pick up and hold an IC device and push it against a test head and being able to move in a region of the test unit.
The loader unit conveyor system picks up and holds an IC device carried on a customer tray by the suction unit and places it on the heat plate, then picks up and holds an IC device on the heat plate heated to a predetermined temperature again by the suction unit and places it on the buffer stage. Further, the buffer stage carrying the IC device moves from the loader unit to the test unit side. Next, the test unit conveyor system uses the contact arm to pick up and hold the IC device on the buffer stage and push it against a socket of the test head to bring the external terminals of the IC device (device terminals) and the connection terminals of the socket (socket terminals) into contact.
In this state, a test signal supplied from the tester body through a cable to the test head is applied to the IC device and a response signal read out from the IC device is sent through the test head and the cable to the tester body to measure the electrical characteristics of the IC device.
However, the stroke of the contact arm along the Z-axial direction when pushing a picked up and held IC device against the socket differs depending on the type of the IC device, so has to be reset each time when changing the type of the IC device under test.
This stroke of the contact arm is generally set by the following teaching operation. First, the theoretical torque is found from the number of contact pins on the socket, the necessary load per pin of the contact pins, the number of sockets on the test head, etc. Next, the contact arm picking up and holding the IC device is moved downward to make the IC device contact the socket. Next, when the actual torque reaches the theoretical torque, the downward movement of the contact arm is stopped. The stroke of the contact arm in this state is taught as the final stroke executed in an actual test.
However, when using this method to teach the stroke, the stroke is not necessarily optimum because it is not possible to judge whether the IC device is reliably in electrical contact with the socket at the time of testing or not unless an actual test is executed.
Further, even if the test is executed normally by the stroke taught by the above method, the lifetime of the socket may be shortened by the IC device being strongly pushed against it when the theoretical torque is unnecessarily strong